Researchers in diagnostic imaging increasingly are voicing concern that as the technological capabilities of imaging methods and modalities are improved, the sheer volume of data produced is becoming overwhelming. For example, ultrasonic imaging is being applied with great success to breast screening, achieving resolutions in the range of 1 millimeter. For such systems, as many as 100 cross-sectional images are needed fully to scan a single breast. When it is contemplated that screening centers will process hundreds of patients per day, it is evident that the technological capabilities efficiently to display and discern detail will far outstrip the physician's ability to utilize and appreciate such detail. Clearly, means must be found to help the physician process this flood of detail.
It has been suggested that computer techniques be employed. Such an approach may prove fruitful when the clinical signs of malignancy become better understood, and when the power of computer pattern recognition techniques increases well beyond its present primitive state; for the present, however, known technology cannot be used profitably for the sort of applications and problems involved in large population screening programs. Clinical signs of occult tumors are subtle, sometimes even evading the careful scrutiny of trained observers. In fact, the relative importance of various signs are now the subject of considerable debate. Accordingly, computer/algorithmic techniques for automatic investigation of screening--diagnostic images are not presently a viable alternative, and for the foreseeable future will continue not to be.
Remarkably, trained clinicians have pattern recognition facilities which subliminally integrate primary, secondary, and tertiary effects and patterns in order to draw diagnostic and pathologic conclusions, provided that the data are conveniently and efficiently presented in space and time. It is, accordingly, a primary object of the present invention to provide image storage and display techniques which permit the clinician to exercise learned and inherent pattern recognition techniques efficiently to detect lesions, malignancies, and abnormalities in tissue structures. An associated object, of course, is to enable such investigations and conclusions to be conducted rapidly and on a high volume basis, whereby high population screening programs become practically, as well as technologically effective.
Once it is determined to utilize direct, human review of the large number of frames entailed in scanning an organ, logical imperatives dictate either viewing them all at once (e.g. in the form of a semi-transparent three-dimensional projection), viewing individual images rapidly sequentially, or viewing smaller numbers at a time, with the aggregate being viewed rapidly sequentially. Having stated the goal or object, however, to be an efficient, accurate presentation, with the observer having full facility for detection of very small and perhaps not particularly clearly defined tissue abnormalities, implementation is quite a difficult proposition.
One relevant class of prior art systems relates to production and display of a three-dimensional projection. Exemplary of this class of system are the schemes set forth in U.S. Pat. Nos. 3,202,985 to Perkins et al., 3,462,213 to deMontebello, and 2,189,374 to Surbeck. Each of those patents, in their own fashion, utilizes some sort of physical oscillation or variable displacement of the point of image projection, on a rapid repeating basis, whereby an aggregate of multiple projections over a predetermined depth range give the viewer an impression of three-dimensionality. The Perkins et al. patent describes utilization of a spherical spiral screen, deMontebello teaches utilization of spiral wheels with projection being directed radially outward from the axis, and Surbeck teaches utilization of a helical, screw-type planar projection screen. All three types, however, rely on spatial variation of the projection surface, which is apprehended by the viewer as a volumetrically continuous, semi-transparent three-dimensional display.
A similar, related class of display utilizes formed, rotating phosphorescent screens within a cathode ray tube, achieving the same effect but in a sealed, electronic format. Exemplary of this class are U.S. Pat. Nos. 3,204,238 to Skellett and 3,140,415 to Ketchpel.
It is an object of the present invention to provide display methods and systems which, if desired, may utilize the foregoing prior art approaches based on variable depth screens and concomitant three-dimension illusions, but which substantially obviate prior art problems of flicker, instability, and mechanical bulk.
A technologically ancient approach to multiple frame viewing relates to utilization of a disk photo record, along the periphery of which is disposed a plurality of sequentially associated images. These systems, such as exemplified in U.S. Pat. Nos. 661,515 to Giel, 1,236,819 to Bulask et al., and others, generally were developed as precursors to modern film-type viewing, with the illusion of motion being obtained by rapid, stroboscopic illumination of sequentially associated images. While these systems were hardly suitable for larger scale motion picture applications, they do teach useful techniques for storage of a rather smaller number of sequentially associated images.
It is an object of the present invention to utilize disk-type photo information records to display usefully and efficiently the number and type of images which might be utilized in clinical or screening applications of diagnostic imaging systems.
While the previously described classes of prior art information storage and display systems are technologically interesting and conceptually generally sound, they are generally premised on elaborate electromechanical workings, and provide numerous structural, mechanical, and the like inconveniences, and further impose considerable dependency of the viewer upon the rigid timing limitations which are fundamental to the system. For example, the nature of the aforementioned 3-D display systems makes it quite difficult, if not impossible, for the viewer to focus attention upon very small, microportions of the tissue image in interest, to "zoom" electronically or optically to areas of greater interest, or to manipulate data for more abbreviated or effective presentation.
It is an object of the present invention to provide systems which afford the viewer the capacity to view tissue images, in the aggregate, either three-dimensionally or in smaller portions, including an image at a time rapidly viewed in sequence, or in partial or total sections viewed three-dimensionally and simultaneously, with respective successive sets being so reviewed rapidly sequentially.